* listensocket_get_listener() must always be called with a matching call
  to listensocket_release_listener
* No ticket for this, but may be related to #2372.
* Found an reported by Xogium on IRC.

See: #2372

Thanks to Xogium for finding and debugging this!

Fixes: #2377

...with OpenSSL 1.1.0 or newer

Instead use TLS_server_method and
SSL_CTX_set_min_proto_version to limit
the used protocol versions.

According to the documentation the current option state is not cleared
but the options are added to the current options, so gettin the
current options seems redundant to the behavior of SSL_CTX_set_options:

> SSL_CTX_set_options() adds the options set via bitmask in options
> to ctx. Options already set before are not cleared!

Assigning the return value of SSLv23_server_method to a variable is
not necessary here and not doing it can get us rid of a lot of
condition code given that the type of the return value changed
at some point.

Explicitly initializing the library is not longer needed since
OpenSSL 1.1.0 and the SSL_library_init function is deprecated.

Citing the manual:

> As of version 1.1.0 OpenSSL will automatically allocate all resources
> that it needs so no explicit initialisation is required. Similarly it
> will also automatically deinitialise as required.

Fix #2318

It conflicts with libressl, which is needed for curl now.

Closes: #2348

Closes: #2358

Allow enabling devil logging in configure using the
--enable-devel-logging switch.
Doing so defines the DEVEL_LOGGING macro.

See: #2358

See: #2370

Closes: #2370